Bridge docking structure for aircraft

ABSTRACT

A system for servicing and maintaining an aircraft includes a fuselage dock assembly having a first ground-supported column, a second ground-supported column and a walkway section supported by the first and second columns. The system also includes a tail dock assembly having a recess defined therein for receiving a tail section of an aircraft, and an engine stand for servicing an engine of the aircraft that is not readily accessible from the fuselage dock assembly or the tail dock assembly. Structure is also provided for adjusting the height and inclination of the walkway section relative to a horizontal plane, so that the walkway section will conform to the natural inclination of a particular aircraft. The system includes several other novel and advantageous features for increasing the safety and efficiency of aircraft maintenance.

This is a continuation-in-part of Ser. No. 640,982, filed on Jan. 14,1991, the disclosure of which is hereby incorporated herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to systems which are used to provide access tocommercial jet aircraft during maintenance. More specifically, theinvention relates to an aircraft maintenance system that is simple todeploy and is more effective at providing access to different types ofaircraft than systems which have previously been used.

2. Description of the Prior Art

Regular and thorough maintenance is necessary to ensure that the largefleets of modern airliners used in commercial aviation are as safe andreliable as possible. For economic reasons, it is important that suchmaintenance be carried out as quickly and efficiently as possible.

In practice, it is sometimes difficult for individual maintenancepersonnel to gain access to desired areas on an aircraft. To addressthis problem, certain roof-suspended scaffolding systems have beendevised. Such a system is disclosed in U.S. Pat. No. 3,602,335 toGustetic. Among other disadvantages, such systems often requirereinforcement of the roof of a maintenance hangar before they can bedeployed. Other, prior art systems include those disclosed in U.S. Pat.Nos. 3,256,955 to Izmirian et al., and 3,831,709 to Stanford et al.

One problem that is common to all three of the above-disclosed systemsis that, generally, they are readily adjustable to receive differenttypes of aircraft. For example, most aircraft have a characteristicdownward inclination from the nose of the fuselage toward the tailsection while they are resting on the ground. Typically, prior artmaintenance systems are not readily adjustable at both ends toaccommodate themselves to such differences between aircraft.Furthermore, prior art systems are not length-adjustable to permitservicing of different sizes of aircraft. These are all significantdisadvantages to the prior art, since most commercial airlines haveseveral different types of aircraft in their fleets.

Another problem not addressed by existing systems is that exit and entryports along the fuselage of the aircraft are typically not arranged in alinear path. In systems that use strictly horizontal access walkwaysalong the length of the fuselage, maintenance personnel are forced totraverse significant vertical upward or downward steps to gain entry tothe fuselage at certain points. This, of course, presents danger,particularly when tools or aircraft components are carried into or outof the fuselage.

Yet another problem that exists in such systems is the difficulty ofgaining access to the various engines of the aircraft. For example, aBoeing 727 airliner has three engines, all in the tail section of theaircraft. To date, no system has been devised which provides adequateaccess to all three engines, particularly when removal of one or more ofthe engines is required.

Other specific aircraft models present access problems as well. Forexample, the size of Boeing 747 aircraft require special arrangements togain access to such portions as the horizontal and vertical stabilizersof the aircraft.

It is clear that there has existed a long and unfilled need in the priorart for an aircraft maintenance facility that can be deployed withoutreinforcement of a maintenance hangar, which is adjustable to theinclination of different types of aircraft, which is verticallyadjustable to provide access to different ports along an aircraftfuselage, and which is readily adaptable to provide access to engines onan aircraft.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide an aircraftmaintenance facility that does not necessitate reinforcement of anaircraft maintenance hangar.

It is further an object of the invention to provide an aircraftmaintenance facility that is adjustable to the characteristicinclination of different types of aircraft.

It is further an object of this invention to provide an aircraftmaintenance facility which provides vertically-adjustable access alongdifferent points of an aircraft fuselage.

It is also an object of the invention to provide ready access to each ofthe different engines of an aircraft.

It is yet further an object of the invention to provide an aircraftmaintenance facility that is quickly deployable in operative positionadjacent an aircraft.

To achieve these and other objects of the invention, a fuselage dockassembly for aircraft maintenance and repair according to a first aspectof the invention includes a first ground-supported column; a secondground-supported column; and a walkway system supported at a firstlocation by the first column and at a second location by the secondcolumn, the walkway system including a structural space frame extendinglongitudinally therealong for torsionally reinforcing the walkwaysection against stress created by components of the walkway section,workers and equipment which are proximate an aircraft.

According to a second aspect of the invention, a fuselage dock assemblyfor aircraft maintenance and repair includes a walkway system;ground-supported structure for moving the walkway system into a workingposition adjacent to a fuselage section of an aircraft; and a platformfor gaining access to a horizonal stabilizer fin of the aircraft, theplatform being mounted to the walkway system so as to moveable intoworking position along with the walkway system.

According to a third aspect of the invention, a fuselage dock assemblyfor aircraft maintenance and repair includes a first ground-supportedcolumn; a second ground-supported column; and a walkway system supportedin a first location by the first column and at a second location by thesecond column; the walkway system including a plurality of verticallyspaced walkways which are positionable adjacent to a vertical stabilizerof an aircraft, whereby access can conveniently be gained to thevertical stabilizer during maintenance of the aircraft.

According to a fourth aspect of the invention, an assembly forsupporting maintenance personnel and equipment during maintenance orrepair of an aircraft includes a platform; at lest one slide boardmounted to the platform so as to be slidably extendable from theplatform, whereby the assembly can be arranged to conform to the shapeof an aircraft; and structure for releasably locking the slide board inposition with respect to the platform, whereby the slide board will notmove during use of the assembly to maintain an aircraft.

These and various other advantages and features of novelty whichcharacterize the invention are pointed out with particularity in theclaims annexed hereto and forming a part hereof. However, for a betterunderstanding of the invention, its advantages, and the objects obtainedby its use, reference should be made to the drawings which form afurther part hereof, and to the accompanying descriptive matter, inwhich there is illustrated and described a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a top plan view of an aircraft maintenance andrepair system constructed according to a preferred embodiment of theinvention;

FIGS. 2A and 2B are a side elevational view of the aircraft maintenanceand repair system illustrated in FIG. 1;

FIG. 3 is a cross-sectional view taken along one point of a walkwaysection in the system illustrated in FIGS. 1 and 2;

FIG. 4 is a fragmentary cross-sectional view taken along a secondportion of the walkway section;

FIG. 5 is a fragmentary isolational view of a first ground-supportedcolumn in the system which is illustrated in FIGS. 1-4;

FIG. 6 is a fragmentary isolational view of a second ground-supportedcolumn which is illustrated in FIGS. 1-5;

FIG. 7 is a fragmentary cross-sectional view through a section of acolumn which is illustrated in FIG. 5;

FIG. 8 is a cutaway top plan view of a forward trolley in the systemwhich is illustrated in FIGS. 1-7;

FIG. 9 is a fragmentary cutaway view of the forward trolley illustratedin FIG. 8;

FIG. 10 is a fragmentary cutaway side elevational view of a second, reartrolley assembly in the system illustrated in FIGS. 1-9;

FIG. 11 is a fragmentary cutaway front elevational view of the reartrolley assembly illustrated in FIG. 10;

FIG. 12 is a fragmentary cross-sectional view of an extendablenose-engaging section in the system illustrated in FIGS. 1-11;

FIG. 13 is a bottom plan view of an extendable slide board assembly inthe system illustrated in FIGS. 1-12;

FIG. 14 is a bottom plan view of a second type of slide board assembly;

FIG. 15 is a lower perspective view of a forward portion of the systemillustrated in FIGS. 1-14;

FIG. 16 is a fragmentary elevational view of an adjustable work platformin the system illustrated in FIGS. 1-15;

FIG. 17 is a rear perspective view of an aft portion of the systemillustrated in FIGS. 1-16;

FIG. 18 is a top front perspective view of an engine access stand withinthe system illustrated in FIGS. 1-17;

FIG. 19 is a schematic view of an H-drive assembly in the engine standillustrated in FIG. 18;

FIG. 20 is a perspective view of one portion of an upper tail accessplatform according to the system illustrated in FIGS. 1-19;

FIG. 21 is a perspective view of a second feature on the upper platform;

FIG. 22 is a perspective view of a third feature on the upper platform;

FIG. 23 is a cross-sectional view of one of the slide board assembliesaccording to the invention illustrated in FIGS. 1-22;

FIG. 24 is a cross-sectional view of a bumper member according to thesystem which is used to protect the fuselage of an aircraft duringmaintenance;

FIG. 25 is a fragmentary diagrammatic cross-sectional view of a guardrail fold-over hinge according to one aspect of the invention;

FIGS. 26(a)-26(e) are diagrammatical views of a facility according toFIGS. 1-25 being deployed in operative position adjacent an aircraft;

FIG. 27 is a perspective view of a facility constructed according to asecond embodiment of the invention;

FIG. 28 is a rear perspective view of the right side dock assembly inthe embodiment of the invention depicted in FIG. 27;

FIG. 29 is a schematic depiction of three different mechanical drivesystems in the embodiment depicted in FIGS. 27 and 28; and

FIG. 30 is a fragmentary perspective view of a slide board lockingsystem which can be utilized in either of the disclosed embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, wherein like reference numerals designatecorresponding structure throughout the views, and referring inparticular to FIGS. 1A and 2A, an aircraft maintenance and repair system10 constructed according to a preferred embodiment of the inventionincludes a first fuselage docking assembly 12 and a second fuselagedocking assembly 14. Docking assemblies 12, 14 are positioned onopposite lateral sides of a fuselage 16 of an aircraft 15, as may beseen in FIGS. 1A and 2. Aircraft 15 further has a nose section 18, aleft wing 20 and a right wing 22. It should be understood that dockingassemblies 12, 14 are substantially identical except that they areconstructed so as to be symmetrically opposite to each other, althoughother minor variations can be made to ensure compatibility withasymmetrical features on different types of aircraft.

Referring primarily to FIG. 2A, each dock assembly 12, 14 includes afirst ground-supported column 24, a second ground-supported column 26and a walkway section 28 which is supported at a first location bycolumn 24 and at a second location by column 26. Both column 24 andcolumn 26 are height adjustable, which allows the height and inclinationof walkway 28 to be adjusted relative to a horizontal plane. In thisway, the walkway section can be adjusted to conform to the naturalinclination of several different types of aircraft. The walkway sectioncould also be vertically lowered to gain access to the landing gear onan aircraft. The specific structure which permits the columns 24, 26 tobe so adjusted is discussed in greater detail below.

Referring again to FIG. 2A, it will be seen that walkway section 28includes an upper level walkway 30 and a lower level walkway 32, foraccessing different vertical portions of the fuselage 16. An inside edge34 of lower level walkway 32 is depicted in FIG. 1A. As can be seen inFIG. 3, the inside surface of upper level walkway 30 extends furtherinwardly than inside surface 34, so as to conform to the outer curvatureof the fuselage 15.

One particularly important feature of the invention is the provision ofa stress reinforcing member 36 which extends along the length of walkwaysection 28. As may be seen in FIGS. 3 and 4, stress reinforcing member36 is embodied as a box-like beam 38, which is constructed to stiffenwalkway section 28 against torsional deformation in response totorsional moments which would be created by weight on upper levelwalkway 30. The specific construction of box-like beam 38 will bediscussed in greater detail below in reference to FIGS. 3 and 4.

Looking again to FIGS. 1A and 2A, walkway section 28 includes a forwardwork platform 40 which is designed to be positioned proximate a forwardentry port of aircraft 15. Shelving 42 is provided integrally on walkwaysection 28 immediately proximate work platform 40, for ready storage oftools or aircraft components. An inter-level stairway 44 is provided ata forward end of work platform 40 for access between walkways 32, 30. Ascan best be seen in FIGS. 2 and 15, a lower stairway section 46 ispivotally mounted at an upper end to walkway section 28, and issupported by the underlying ground surface on a second, lower end bycasters 62. As a result, lower stairway section 46 will continuouslyadjust relative to the ground as walkway section 28 is raised orlowered. Casters 62 permit lower stairway section 46 to move with dockassembly 12, 14 during deployment of the dock assembly 12, 14 inposition adjacent to an aircraft 15.

Each dock assembly 12, 14 further includes an extendable nose-engagingportion 52, as can best be seen in FIGS. 1A, 12 and 15. Each extendablenose-engaging portion 52 includes a plurality of slide board members 54which are individually extendable to conform to the outer dimensions ofnose section 18 of aircraft 15. The various features of nose engagingportion 52 will be discussed in greater detail below.

As may be seen in FIG. 2A, first ground-supported column 24 is mountedon a forward trolley unit 56, which will be described in greater detailwith reference to FIGS. 5, 8 and 9. An electric motor 58 is mounted on atop end of column 24, for controlling the height adjustment thereof. Analignment mechanism 60 is further provided to ensure that the componentsof columns 24 remain aligned during extension and retraction.

According to one important feature of the invention, a plurality ofadjustable work platforms 64 are provided within the main truss system70 of walkway section 28. By individually adjusting the level of thevarious work platforms 64, walkway section 28 can be made to conform tothe various ports and entry ways on different types of aircraft. This isan important advantage, since the various ports and entry ways onaircraft are frequently not in linear alignment.

Other features of walkway section 28 include a plurality of fluorescentlights 66, most of which are mounted on the lower surface of upper levelwalkway 30 to illuminate the area beneath. An electrical distributionpanel 68 is part of an overall electrical distribution system whichprovides power to the fluorescent lamps 66, as well as to numerouselectrical outlets throughout the walkway section 28. Dock assemblies12, 14 further include a system for distributing compressed air, and mayalso be adapted to distribute heat or air conditioning into the fuselageby using box-like beam 38 as a distribution manifold.

Referring now to FIGS. 3 and 4, each box-like beam 38 includes an outerskin 74 which is metallic and rectangular in cross-section, as may beseen in FIG. 3. Periodically along the length of beam 38 are positionedinterior framing members 76, which are also rectangular in cross-sectionand are fabricated by four heavy duty steel structural elements weldedtogether in rectangular fashion. A plurality of stiffener elements 78each having a U-shaped cross-section extend longitudinally withinbox-like beam 38 between outer skin 74 and the outer edges of interiorframing member 76. Upper level walkway 30 is welded to a lower surfaceof outer skin 74, as may be seen in FIG. 3. When weight is placed uponupper level walkway 30, a torsional force will be transmitted in aclockwise direction to box-like beam 38. This force is transmittedthrough stiffeners 78 to the interior framing member 76 which provideadditional resistance against deformation. As a result, upper levelwalkway 30 may be made as long as necessary to service a fuselage 16,without fear of torsional deformation.

FIG. 4 illustrates box-like beam 38 at a joint portion 80 which joinsvarious sections of outer skin 74. At joint portions 80, a joint framingmember 82 formed from heavy steel structural elements into a rectangularshape is provided for coupling the outer skin portion 74 and thestiffeners 78. For further reinforcement against torsional deformationat this point, a diagonal brace 84 is further provided within the jointframing member 82.

Referring now to FIGS. 5 and 7, the construction of firstground-supported column 24 and accessories thereto will now be describedin detail. As may be seen in FIG. 5, first ground-supported column 24includes a first tubular member 86 which is telescopingly receivedwithin a second, upper tubular member 88. Alignment mechanism 60maintains first tubular member 86 in rotational alignment with respectto second tubular member 88 as the members 86, 88 are moved relative toeach other. As may be seen in FIG. 5, alignment mechanism 60 includes anupper collar 90 which is mounted to second tubular member 88, and alower collar 94 which is mounted to first tubular member 86. An uppercross bar 92 and a lower cross bar 96 are mounted to the upper and lowercollars 90, 94, respectively. A first arm 104 and a second arm 106 arehingedly mounted to opposite ends of upper cross bar 92 by first andsecond hinges 100, 102, respectively. Similarly, a third arm 108 and afourth arm 110 are hingedly mounted to opposite ends of lower cross bar96 by a third hinge 112 and a fourth hinge 114, respectively. First,second, third and fourth arms 104, 106, 108 and 110 are connectedtogether at second, opposite ends thereof by a common hinge mechanism116 as may be best seen in FIG. 15.

Referring again to FIGS. 5 and 7, the jack screw mechanism for raisingand lowering first ground-supported column 24 will now be described indetail. As may be seen in FIG. 7, a gear reduction unit 118 is providedfor transmitting power from an electric brake-motor assembly 58 to ashaft 120 via a coupling 122. Brake-motor assembly 58 is a commerciallyavailable unit that applies a braking action to its output shaft at alltimes other than when power is being supplied to turn a motor therein.Shaft 120 is mounted for rotation relative to a cover plate 126 on topof second tubular member 88 by a thrust roller bearing 124. As mayfurther be seen in FIG. 7, shaft 120 includes a lower threaded shaftportion 128 on an end thereof which is positioned thrust roller bearing124. Threaded shaft portion 128 is threadedly engaged with a threadedfollower member 130, which is mounted to a cover plate 132 via bolts134. Cover plate 132 is secured to a top end of first tubular member 86.It will be appreciated that rotation of shaft 120 by motor 58 will causesecond tubular member 88 to either extend or retract from first tubularmember 86, depending upon the direction of rotation. In this way, theextension of first ground-supported column is controlled, and the heightand inclination of walkway 28 may be adjusted relative to a horizontalplane. Limit switches (not shown) are also provided to limit relativeextension and contraction of the members 86, 88 beyond predeterminedupward and downward limits by cutting off power to the motor 58.

As may further be seen in FIG. 7, a plurality of composite slidebearings 136 are mounted to the cover plate 132 on top of first tubularmember 86. In the preferred embodiment, at least three slide bearings136 are provided between the tubular members 86, 88 and are spaced ateven intervals along the upper circumference of first tubular member 86.Slide bearings 136 ensure smooth, slop-free movement between the members86, 88. As may be seen in FIG. 5, a plurality of retention bearings 148are mounted to a lower end portions of second tubular member 88 tofurther stabilize movement between the elements 86, 88 and to preventthe elements 86, 88 from slipping apart. A stop plate 138 is furtherprovided at a lowermost end of shaft 120 for limiting upward movement ofsecond tubular member 88 with respect to cover plate 132.

FIG. 6 depicts the specific construction of second ground-supportedcolumn 26. Second ground-supported column 26 includes a jack screwarrangement 140 which is substantially the same as that which isprovided for first ground-supported column 24. A gear reduction unit 142is provided for transmitting power from electric motor 72 to the jackscrew arrangement 140. Jack screw arrangement 140 telescopingly adjuststhe position between a first tubular member 144 and a second tubularmember 146.

A rotatable pivot sleeve 150 is mounted for rotation about secondtubular member 146. Retention bearings 154 are provided to maintainpivot sleeve 150 in alignment with second tubular member 146. A supportarm 152 extends from rotatable pivot sleeve 150 for supporting an engineinlet access plank 360, as may be seen in FIG. 17. A rotary mechanicaltransmission which is powered by a crank 362 is also mounted to an outersurface of pivot sleeve 150 for rotating sleeve 150 relative to secondtubular member 46. The purpose of plank 360 will be discussed in greaterdetail below.

Referring now to FIGS. 5, 8 and 9, the specific construction of forwardtrolley assembly 156 will now be described in detail. Forward trolley156 includes a first large wheel 158 and a second large wheel 160. Firstlarge wheel 158 is mounted to rotate in a plane which is slightly angledwith respect to the plane in which second large wheel 160 is mounted torotate. As a result, each forward trolley assembly 156 will move in aradiused path, the significance of which will be discussed below withreference to FIGS. 26(a)-26(e). Trolley assembly 156 further includes aplurality of smaller wheels 162 which are mounted laterally on the outerends of trolley assembly 156. The smaller wheels 162 are mounted torotate in planes which are substantially perpendicular to the paths inwhich large wheels 158, 160 are mounted to rotate in. Specifically, thepath in which large wheels 158, 160 are mounted to rotate in issubstantially perpendicular to the longitudinal axis of fuselage 15,while the planes in which wheels 162 rotate in are parallel to the axis.

As may be seen in FIG. 5, forward trolley assembly 156 includes an outerhousing 164 which is secured to a lower end of first tubular member 86.A pneumatic actuator housing 166 is mounted to an upper portion of outerhousing 164. A pneumatic cylinder 168 is mounted within housing 166. Apiston having a shaft 170 is sealingly provided within cylinder 168 forextension and retraction according to pneumatic pressure within cylinder168. As is best shown in FIG. 9, piston shaft 170 is connected at alower end to a lever arm 172 via a pivot connection 174. Lever arm 172is itself pivotally mounted about a pivot point 176 with respect to avertical support member 177 that is fixed relative to outer housing 164.Lever arm 172 is mounted to a linkage 178 at a second opposite end fromits connection to piston arm 170 by a pivot connection 179. A second,opposite end of linkage 178 is connected to first ends of a first wheelsupport arm 182 and a second wheel support arm 183 via a pivotconnection 180.

As is further shown in FIG. 9, first wheel support arm 182 is pivotallymounted with respect to housing 164 by a pivot connection 184. Aplurality of the small wheels 162 are fixedly mounted to first wheelsupport arm 182 on an opposite side of pivot connection 184 from linkage178. Similarly, the second set of small wheels 162 are connected tosecond wheel support arm 183 on an opposite side of pivot connection 185from the pivot connection 180 which connects linkage 178 and secondwheel support arm 183. From the above it will become apparent thatextension of piston shaft 170 will cause linkage 178 to be pulledupwardly, thereby causing both sets of small wheels 162 to movedownwardly beneath the lowermost points on the first and second largewheels 158, 160. As a result, forward trolley assembly 156 will restentirely upon the small wheels 162. When piston shaft 170 is retracted,small wheels 162 will likewise retract, thereby leaving the entireweight of forward trolley assembly 156 on the first and second largewheels 158, 160.

Forward trolley assembly 156 further includes a pneumatic motor 186which includes an output sprocket 188 that is connected to a drive chain190. Drive chain 190 is engaged with a wheel sprocket 192 on secondlarge wheel 160. An adjustable guide sprocket 194 is also engaged withdrive chain 190 for adjusting the tension on drive chain 190. When motor186 drives output sprocket 188, power is transmitted to second largewheel 160 via drive chain 190 to move the trolley assembly 156 in anarcuate motion which is dictated by the differing inclinations of firstlarge wheel 158 and second large wheel 160. The movement of trolleyassemblies 156 in relation to the overall system will be discussed ingreater detail below.

Referring now to FIGS. 10 and 11, the specific instruction of the reartrolley assembly 198 will be described in detail. As may be seen in FIG.11, rear trolley assembly 198 includes an outer housing 204 which issecured to a lower end of first tubular member 144. Referring brieflyback to FIG. 1B, the rear trolley assemblies 198 of the differentfuselage dock assemblies 12, 14 are mounted on second and first guiderails 202, 200, respectively. Guide rails 202, 200 are preferablymounted in an underlying concrete surface within an aircraft maintenanceand repair hangar. As may be seen in FIG. 1, each rail 200, 202 isangled outwardly and rearwardly with respect to a line that isperpendicular to a longitudinal axis of fuselage 16.

Referring back to FIG. 11, a first rail clamp 206 and a second railclamp 208 are connected to opposite ends of outer housing 204 forengaging the rail 200, 202 upon which trolley assembly 198 is mountedfor guidance. Rail clamps 206, 208 effectively engage the contour ofrails 200, 202 to stabilize the fuselage assembly 12, 14 when externalforces begin to tip the assembly. A first track wheel 210 and a secondtrack wheel 212 are further provided and are engaged with the respectiverail as well. A pneumatic motor 214 is mounted within outer housing 204and includes a drive sprocket 216 which is engaged with a drive chain218. Drive chain 218 is also engaged with a wheel sprocket 220 on secondtrack wheel 212. A guide sprocket 222 is also engaged with drive chain218 for adjusting the tension thereof. In this way, pneumatic motor 214can rotate second track wheel 212, and thus move rear trolley assembly198 on the respective rail 200, 202.

Turning now to FIG. 12, the specific construction of extendable noseengaging section 52 will now be described in detail. Nose engagingsection 52 includes a frame 226 which is longitudinally slidablerelative to the lower level walkway 32 of walkway section 28. Frame 226includes a plurality of horizontally oriented housing members 228 for acorresponding number of slide boards 230. As can be seen in FIG. 15,slide boards 230 allow the inward most edge nose engaging section 52 tobetter conform to the external dimensions of the nose section 18 of thefuselage 16. A guard rail member 232 having an upper horizontal ramp234, a lower horizontal rail 236 and a plurality of vertical rails 238is provided on the edges of a horizontal work platform 240 that are notpositionable adjacent to fuselage 16. As may be seen in FIG. 12, workplatform 240 is also part of frame 226. Frame 226 further includes astabilizer arm 242 which extends horizontally towards an outer edge oflower level walkway 32. As can be seen in FIG. 12, a raised track 246 isprovided in alignment beneath the vertical frame reinforcing members 290on lower level walkway 32. A wheel 244 is rotatably mounted to avertical arm on a distal end of stabilizer arm 242. Wheel 244 ispositioned to ride upon track 246. Also mounted to a lower surface oflower level walkway 32 is a longitudinal track 250 that is shaped in theform of an I-beam. I-beam track 250 is engaged on opposite sides thereofby a first wheel 252 and a second wheel 254, both of which are mountedfor rotation by brackets which are mounted to a break arm 256. A breakpad 262 is also mounted to a top surface of break arm 256, immediatelybeneath a bottom surface of I-beam track 250. Break arm 256 is itselfpivotally connected to a bracket 258 at a pivot connection 266. Bracket258 is integral with frame 226, as may be seen in FIG. 12.

As further shown in FIG. 12, a lever 264 is pivotally mounted to avertical rail 238 of guard rail member 232. Lever 264 is connected to abrake linkage 268 via an over-center toggle linkage 266. A second,opposite end of brake linkage 268 terminates in a hook member 270, whichis adapted to engage a notch on an end portion of brake arm 256 which isopposite from pivot point 266. As can be seen in FIG. 12, brake linkage268 is formed in two separate lengths, which are connected together byone or more bolts through adjustment holes 272. In this way, theabsolute length of brake linkage 268 can be adjusted.

When lever 264 is in its upward position, as shown in FIG. 12, brakelinkage 268 urges break arm 256 to pivot about point 256 in acounterclockwise direction, thereby urging break pad 262 against thebottom surface of I-beam track 250. As a result, nose engaging section52 is locked in a desired position with respect to walkway section 28.If an operator desires to extend or contact the overall length of afuselage dock assembly 12, 14, he may pivot lever 264 downwardly,thereby disengaging break pad 262 from the bottom surface of I-beamtrack 250. The entire nose engaging section 52 will then be supportedfor rotation relative to walkway section 28 by rollers 244, 252 and 254.Nose engaging section 252 can be slid longitudinally to adjust to thelength of fuselage 16 at this point, and then may be relocked relativeto walkway section 28 by returning lever 264 to the locked position.Once locked in the desired position, one or more chains may be stretchedacross the nose section 18 of fuselage 16 from the hooks 248 which areprovided on guard rail members 232 of the adjacent dock assemblies 12,14.

Referring to FIGS. 12-15, the construction of the slide board assemblieswill now be discussed. Each slide board 230 is formed from plate metalto have a top surface, a pair of side surfaces and a pair of oppositelyfacing bottom flanges, leaving an open space therebetween. At one pointalong the bottom of each slide board 230, a bottom plate 278 is weldedto the bottom flanges, thereby giving slide board 230 a completerectangular cross-section along the length of bottom plate 278. Eachbottom plate 278 has a threaded hole defined therein for receiving aretention bolt 284, as can be seen in FIGS. 12-14. Each housing 228likewise is formed of plate metal and includes a top surface, two sidesurfaces and flanges 274, 276 at the bottoms thereof. An open bottomportion 280 is defined between flanges 274, 276. As shown in FIG. 15, areinforcement bar 286 extends transversely in a desired configurationacross the different housing members 228. The innermost ends of slideboards 230 are provided with bumpers 282, which are preferably formed ofshort lengths of polymeric tubing. By extending each slide board 230 sothat bumper 282 bears against the side of fuselage 216, those engagingsection 52 will conform to the external curvature of nose section 18 ofthe aircraft 15. Bar reinforcement 286 acts in conjunction with theretention bolts 284 to prevent the slide boards 230 from being pulledtoo far out of the respective housings 228. The bumper elements 282 canbe mounted transversely with respect to the axis of slide boards 230, asis shown in FIG. 14, or at an angle to better conform to the nosesection 18, as is illustrated in FIG. 13.

Referring now to FIGS. 2 and 16, the specific construction of adjustablework platform 64 will now be discussed in detail. As shown in FIG. 2,walkway section 28 includes a main truss system 70 which is formed by aplurality of upper longitudinal frame elements 288, lower longitudinalframe elements 296, vertical frame reinforcing members 290 and diagonalframe reinforcing members 292. The stationary lower walkway surface 294is suspended from box-like beam 38 and upper longitudinal frame element288 by diagonal frame reinforcing member 292 and vertical framereinforcing member 290, as can be seen in FIG. 16. Lower longitudinalframe element 296 is integral with lower walkway surface 294, andprovides additional rigidity thereto.

Adjustable work platform 64 includes an adjustable lower walkway surface298 which is vertically adjustable with respect to stationary lowerwalkway surface 294. As shown in FIG. 16, adjustable lower walkwaysurface 298 is in one position abutted against stationary lower walkwaysurface 294 at a joint 322. A first cable 300 is secured to lowerlongitudinal frame element 296 by a connection 302. First cable 300 isconnected at a second end to second and third cables 308, 310 via achain 304 and a ratchet winch 306, which is constructed to selectivelylengthen or shorten chain 304. As may be seen in FIG. 16, the second andthird cables 308, 310 are supported for movement about a first guidepulley 312, which is mounted to upper longitudinal frame element 288.Second cable 308 is supported for movement about a second guide pulley314, and is connected at a second end to the adjustable lower walkwaysurface 298 via a connection 318. Second guide pulley 314 is likewisemounted on upper longitudinal frame element 288. Third cable 310 isarranged to pass about a third guide pulley 316 which is also mounted toupper longitudinal frame element 288 above a second, opposite end ofadjustable lower walkway surface 298. Third cable 310 has a second endwhich is connected to the second, opposite end of adjustable lowerwalkway surface 298 via a connection 320. It will be apparent thatadjustable lower walkway surface 298 will be raised with respect tostationary lower walkway surface 294 when an operator uses ratchet winch306 to effectively shorten chain 304. In this way, an operator canadjust the level of adjustable walkway surface 298 to correspond to thevertical position of a selected port, entryway, or aircraft servicepoint in the fuselage 16 of aircraft 15. Adjustable lower walkwaysurface 298 may also be lowered beneath the level of walkway surface 294by allowing chain 304 to ratchet out of winch 306.

Referring back to FIG. 3, it will be seen that a pair of horizontalguard rails 330 are mounted to outer edges of the vertical framereinforcing members 290, in order to prevent maintenance personnel fromfalling off of the walkway surfaces 298, 294. A pair of vertical rails324 are mounted to the adjustable lower walkway surface 298, as is alsoshown in FIG. 3. A first guide member 326 and a second guide member 328are provided on each of the vertical frame reinforcing members 290 toconstrain the adjustable work platform 64 into vertical movement only.

Referring briefly to FIGS. 3 and 24, it will be noted that the insideedges of both upper level walkway 30 and lower level walkway 32 areprovided with resilient contact bumpers 332, 334, respectively. As shownin FIG. 24, contact bumper 332, which is substantially identical inconstruction to contact bumper 334, is mounted to upper level walkway 30by a hollow mounting beam 334 via mounting bolts 342. The bumper 332itself is formed as a resilient gasket member 336 having a toughresilient outer surface 338 and a foam rubber core 340. Preferably,raising an outer surface 338 is formed from a material such asreinforced neoprene.

Referring briefly to FIG. 17, the rearward end of fuselage dock assembly12, 14 include an engine inlet access plank 360, which is deployable togain access to the inlet of the Number 2 engine 348 on a Boeing 727 orlike aircraft. Access plank 360 is supported by a support arm 152, whichis welded to rotatable pivot sleeve 150, as shown in FIG. 6. Rotatablepivot sleeve 150 is mounted for rotation about the second tubular member146 on second ground-supported column 26, and includes a plurality ofretention bearings 154 for supporting the weight of the sleeve 150 andengine access plank 360 relative to second tubular member 146. A manualcrank 362 is provided on one side of pivot sleeve 150, as shown in FIG.17. Crank 362 is connected to a transmission assembly (now shown) whichis conventional in nature for rotating sleeve 150 and, hence, supportarm 152 and plank 360 relative to second tubular member 146. By turningcrank 362, an operator can rotate plank 360 toward or away from thefuselage 16 of aircraft 15 in order to gain access to the cowling of theNumber 2 engine 348.

Referring now to FIGS. 1B, 2, 17-22 and 25, system 10 further includes atail stand arrangement 344 for permitting access to a vertical tailsection 343 and a number 2 engine 347 of aircraft 15, which in theillustrated embodiment is a Boeing 727 airliner. A pair of stands 346are further provided within system 10 for gaining access to the number 1and number 3 engines of aircraft 15.

Referring to FIG. 2B, tail stand arrangement 344 includes a horizontalvertically movable upper platform 348 which is supported on ahorizontal, fixed mid-level platform 350 by four evenly spaced jackscrews 354. Mid-level platform 350 is fixed so as to be integral withthe inside wall of a maintenance hangar facility. A stair 352 isprovided for allowing aircraft maintenance personnel to walk frombetween mid-level platform 350 and a floor of the aircraft maintenancehangar.

Tail stand arrangement 344 further includes a number 2 engine stand 342,which is suspended from mid-level platform 350. Number 2 engine stand342 is positioned for gaining access to the number 2 engine 347 ofaircraft 15, which is a Boeing 727.

Referring to FIGS. 2B and 22, upper platform 348 is guided for linearmovement with respect to the inner wall of an aircraft maintenancehangar or facility or a track member 356. Track member 356 is mounted soas to extend longitudinally vertically along an inner wall of theaircraft maintenance facility by a mounting plate 390. Upper platform348 is mounted to a trolley bracket 392 via an axially adjustableconnection 396, as is shown in FIG. 22. Trolley bracket 392 includes aplurality of trolley wheels 394 for engaging a track portion of trackmember 356. Through the stabilization provided by track member 356,upper platform 348 will remain horizontal and evenly spaced from thewall of the facility when raised or lowered by jack screws 354. As shownin FIG. 2B, a stairway 358 is pivotally mounted to upper platform 348with a lower end thereof resting upon mid-level platform 350. As aresult, stair 358 provides access between upper platform 348 andmid-level platform 350 regardless of the vertical adjustmenttherebetween.

As shown in FIG. 21, upper platform 348 is provided with a plurality ofslide boards 366 which are mounted within housings within upper platform348 and are expandable to conform to the outer dimensions of tailsection 343 during maintenance of aircraft 15. Each slide board 366 isprovided with a bumper 368 on a distal end thereof. The construction ofslide boards 366, bumpers 368 and the housings therefor are identical tothose described above in reference to the slide boards on extendablenose engaging section 52.

As shown in FIG. 20, upper level 348 is further provided with a decksection 370 which is pivotable away from the main portion of upperplatform 348 to permit engines 345, 347, 349 to be accessed by atraversable overhead crane. In the preferred embodiment, swingable decksection 370 is pivotable through a bell crank arrangement 374 which isactuatable by a manual linkage 376, as is shown in FIG. 20. A supportarm 372 is pivotally mounted to the remainder of upper platform 348 andsupports deck section 370.

Another feature of upper platform 348 is the provision of the number ofthe height adjustable guard rails 378, which have a lower rail section382 and an upper rail section 380. Upper rail section 380 is arranged topivot downwardly about a hinge 384, as is shown in FIG. 25. A firstarcuate stop member 386 on upper rail section 380 and a second arcuatestop member 388 on lower rail section 382 are provided to stabilizeupper rail section 380 when it is locked in the upward position, as isshown in FIG. 20. Fold-over guard rails 370 increase the flexibility ofsystem 10 for use when maintaining different types of aircraft.

A stand 346 for gaining access to the number 1 and number 3 engines ofan aircraft is illustrated in FIGS. 2, 18 and 19 of the drawings. As maybe seen in FIG. 18, engine stand 346 includes a work platform 398 whichis vertically adjustable with respect to an engine 349 of aircraft 15. Astairway 402 is pivoted at its upper end to adjustable work platform398, and is supported on the floor of the facility on a second, lowerend by casters 404. Casters 400 are provided to support a frame 416 ofthe engine stand 346. To vertically adjust platform 398 relative to theframe 416 of engine stand 346, as well as with respect to engine 349, anelectric motor 418 is connected to a first shaft 424, as is shown inFIG. 19. First shaft 424 is connected to a second shaft 426 and a thirdshaft 428 via a transfer case 420. Second shaft 426 is connected to afirst jack screw 408, and third shaft 428 is connected to a third jackscrew 412. Motor 418 is a second end of first shaft 424, is connected toa fourth shaft 432 and a fifth shaft 434 through a transfer case 422.Fourth shaft 432 is connected to drive a second jack screw 410 and fifthshaft 434 is connected to drive a fourth jack screw 414. When anoperator actuates motor 418, the above-described "H-drive" transmissionwill ensure that the four jack screws 408, 412, 410, 414 willsimultaneously turn at an identical speed. As a result, work platform398 remains completely horizontal during vertical adjustment.

The jack screws 354 for vertically adjusting upper platform 348 withrespect to mid-level platform 350 are controlled through a transmissionthat is identical in all relevant respects to that described above withreference engine stand 346.

With reference to FIGS. 26(a)-26(e), the deployment and operation of asystem 10 according to the invention will now be described. Referringfirst to FIG. 26(a), the second fuselage dock assembly 14 is initiallypositioned with its rearward end spaced outwardly along first rail 200from the fuselage 16 of an aircraft 15 as aircraft 15 is backed into amaintenance hangar. The forward end of second fuselage dock assembly 14is at this time positioned radially outwardly from fuselage 16 to theextent necessary to clear the left wing 20 of the aircraft as it isbacked into the hangar. Rear trolley assembly 198 on the rearward end ofassembly 14 must be spaced far enough outwardly from fuselage 16 so asto clear the tail section and the number one engine 345 of the aircraft15. At this time, the first fuselage dock assembly 12 is symmetricallypositioned on the opposite side of the aircraft.

Once the aircraft 15 is backed far enough into the maintenance hangar soas to assume the position with respect to tail stand arrangement 344which is illustrated in FIG. 2, the fuselage dock assemblies 12, 14 aredeployed into operative position adjacent fuselage 16. To accomplishthis, pneumatic cylinder 168 and forward trolley assembly 156 isretracted, thereby lifting small wheels 162 so that forward trolleyassembly 156 rests upon the first and second large wheels 158, 160.Power is then supplied to motor 186 to drive the second large wheels160. Since first large wheel 158 is slightly inclined with respect tosecond large wheel 160, so forward trolley assembly 156 negotiates aradially curved path. As a result, the forward end of second fuselagedock assembly 14 negotiates a curved path to the position which isillustrated in FIG. 26(b), while the rearward end thereof staysrelatively stationary. Pneumatic cylinder 168 is then extended, tore-deploy the small wheels 162 on forward trolley assembly 156. At thispoint, motor 214 and rear trolley assembly 198 is actuated to move therearward end of second fuselage dock assembly 14 to the position whichis illustrated in FIG. 26(c). During such movement, the forward trolleyassembly 156 slides longitudinally forward on small wheels 162.Pneumatic cylinder 168 is then again retracted, and motor 186 isactuated to move the forward end of fuselage dock assembly 14 to theposition illustrated in FIG. 26(d), immediately adjacent the outersurface of fuselage 16. The rear end of assembly 14 is then moved byrear trolley assembly 198 to its final inward position adjacent fuselage16, as shown in FIG. 26(e).

Simultaneously or sequentially, the first fuselage dock assembly 12 maybe simultaneously deployed on the opposite side of fuselage 16.

Once fuselage dock assemblies 12, 14 are in position, normal maintenancemay be performed on the aircraft 15. Adjustable work platform 64 may beraised or lowered to gain access to a desired port or entryway onaircraft 15. Upper tail platform 348 may likewise be raised or loweredto correspond to the outer dimensions of the vertical tail section 343of aircraft 15. The Number 1 and 3 engine stands 346 may likewise beadjusted vertically to service the Number 1 and 3 engines 345, 349 onthe opposite sides of aircraft 15. The height and elevation of walkwaysection 28 may be adjusted to correspond to the elevation andinclination of fuselage 16. It should be noted that the entire assemblycould be lowered to gain access to the landing gear of the aircraft aswell.

While the fuselage dock assemblies 12, 14 are deployed next to fuselage16, the nose-engaging sections 52 may be extended or retracted tocorrespond to the length of aircraft 15. To adjust the degree ofextension of section 52, lever 264 is moved to the downward position,thereby releasing brake pad 262 from the lower surface of I-beam track250. The entire assembly 52 is then manually pushed or pulled to theselected position, upon which time lever 264 is again moved to itsupward position, as shown in FIG. 12.

Once the desired maintenance has been performed on aircraft 15, fuselagedock assemblies 12, 14 are withdrawn from their operative position withrespect to fuselage 16, by repeating, in reverse, the incrementalmovements which have previously been discussed with reference to FIGS.26(a)-26(e).

A system 510 constructed according to a second, preferred embodiment ofthe invention is depicted in FIGS. 27-29. As may be seen in FIG. 27,system 510 is specifically designed to be used for servicing andmaintaining a Boeing 747 series aircraft, although aspects of the system510 may, of course, be used during the maintenance of other types ofaircraft as well.

Referring to FIG. 27, system 510 includes a nose docking assembly 514having a left side 522 and a right side 524, a left side dockingassembly 516 and a right side docking assembly 518. The left sidedocking assembly 516 is identical to the right side docking assembly518, although symmetrically opposite thereto with the exception thatfirst and second adjustable walkways 604, 606 (discussed below) can beomitted or made nonadjustable on one of the units if that side of theaircraft does not contain a cargo door. The details of construction ofthe docking assemblies 516, 518 are described in greater detail below.

The left side unit 522 of the nose docking assembly 514 is constructedas a separate unit from the right side unit 524, and is identical inconstruction to the right side unit 524, although it is symmetricallyopposite to the right side unit 524 in its orientation. Both left sideunit 522 and right side unit 524 include plurality of vertically spacedplatform levels upon which maintenance personnel and equipment may besupported. In the preferred embodiment, those constitute a first lowerlevel 526, a second level 528, a third level 530 and a fourth, uppermostlevel 532. Slide boards 546 are provided on the inner edges of thevarious levels 526, 528, 530, 532 for permitting lateral adjustment ofthe inside edge of the respective platform to conform to the outersurface of a nose portion 520 of the aircraft 512. Slide boards 546 aresubstantially identical in construction to the slide beards describedwith reference to the previous embodiment, although they may be providedwith the locking feature described in reference to FIG. 30 below.

Both the left side unit 522 and the right side unit 524 of the nosedocking assembly 514 are further provided with a drive system 534 forvertically adjusting the units 522, 524 so that maintenance personnelcan gain access to a desired area of the nose section 520 duringservicing. Each vertical drive system 534 preferably includes anelectric motor 536 which is connected to drive a first jack screw 538and, via a transfer shaft 540 and a transfer case 544, a second jackscrew 542. At least one of the four levels 526, 528, 530, 532 includes apair of threaded plates for receiving the respective jack screws 538,542. When motor 536 turns the jack screws 538, 542, the respective unit522, 524 will rise or fall with respect to the aircraft 512, dependingupon the direction of rotation of motor 536. Preferably, each unit 522,524 is supported by a pair of outer columns having a sleeve mountedthereover which is secured to the unit 522, 524. As a result, the unit522,524 is vertically adjustable with respect to the support column, andthus to the aircraft 512. The columns will provide support for theweight of the unit 522, 524 and resist the toppling moment which isgenerated by the weight of the unit 522, 524 and any persons andmaterial thereon. The operation of nose docking assembly 514 inconjunction with the overall operation of the system is discussed ingreater detail below.

Referring again to FIG. 27, the left and right side docking assemblies516, 518 are each constructed in a bridge-like configuration, spanningthe left and right wings 548, 550 of the aircraft 512, respectively.Each of the docking assemblies 516, 518 is supported by a first column554 mounted on a forward trolley unit 556, and a second column 560mounted on a rear trolley unit 562. Forward trolley unit 556 isidentical in construction to the rear trolley unit 198 disclosed in theprevious embodiment, and is mounted so as to be constrained to ride on afloor mounted rail track (not shown). The rail track and the assemblies516, 518 in general are oriented as depicted in FIG. 26a-26e, except forthe direction in which aircraft 512 is pointed. Rear trolley unit 562 isidentical in construction to the forward trolley unit 156 disclosed inthe first embodiment of the invention, and has wheels aligned to followa broad, circular path, as is shown in FIG. 27. Like the columns in thepreviously disclosed embodiment, first column 554 and second column 560are extendable to raise or lower the respective docking assembly 516,518 with respect to the aircraft 512.

As is best shown in FIG. 27, a structural space frame 564 is providedwhich extends longitudinally between the first column 554 and the secondcolumn 560 on each of the docking assemblies 516, 518. Space frame 564,like the box like beam 38 in the previous embodiment, is constructed tostiffen the docking assembly 516, 518 against torsional or bendingdeformation in response to torsional moments or weight which may beplaced on a walkway system 566 of the assembly 516, 518.

Walkway system 566 includes a number of platforms which are affixed withrespect to the structural space frame 564, for supporting personnel andequipment during cleaning and maintenance of the aircraft 512. Walkwaysystem 566 further includes a plurality of vertically spaced walkways596 for gaining access to the vertical stabilizer 598 of aircraft 512,an adjustable platform 568 for gaining access to a horizontal stabilizer570 of the aircraft 512, and first and second adjustable walkways 604,606. Stairs 600, 602 are provided for gaining access to the verticallyspaced walkways 596, as may best be seen in FIG. 28.

The vertically adjustable horizontal stabilizer platform 568 is bestshown in FIG. 28. Platform 568 includes an upper level 572, a lowerlevel 574 and a fixed staircase for moving between the levels 572, 574.According to one particularly advantageous feature of the invention,upper level 572 has an inclined surface portion 576 which is inclined atan angle B, which is substantially commensurate with an angle A at whichthe horizontal stabilizer fin 570 is inclined at with respect to thehorizontal. When platform 568 is positioned immediately beneath thehorizontal stabilizer fin 570, this allows maintenance personnelconvenient access to the horizontal stabilizer fin 570 along its entirelength. As shown in FIG. 28, the distal end of the inclined surfaceportion 576 of platform 568 includes a portion 578 which is foldableupon itself to a storage position. This reduces the width of the dockassemblies 516, 518 during storage, which permits deployment of thesystem 510 in a smaller hanger or maintenance building than wouldotherwise be possible.

Horizontal stabilizer platform 568 is vertically adjustable upwardly ordownwardly by means of a vertical adjustment drive system 580. Drivesystem 580 includes a motor 582 which drives a first jack screw 584 andanother jack screw 594 via a transfer shaft 590 and a transfer case 614,as is shown schematically in FIG. 29. Jack screw 584 is threaded into aplate 586 which is welded onto a sleeve 588, as is shown in FIG. 28.Sleeve 588 is provided with internal bearings which allow it to movevertically with respect to second column 560. Horizontal stabilizerplatform 568 is welded to sleeve 588, and includes a second threadedplate through which the second jack screw 594 is threaded. When motor582 turns in a first direction, jack screws 584, 594 are simultaneouslyturned in the same direction and at the same rate, causing thehorizontal stabilizer platform 568 to be raised or lowered. Platform 568will, of course, be adjusted in an opposite direction when motor 582 isturned in a reversed direction.

Referring to FIGS. 27 and 29, first adjustable walkway 604 is verticallyadjustable so as to be positionable adjacent to the upper level 572 ofhorizontal stabilizer platform 568. A drive system for effectingvertical adjustment of first adjustable walkway 604 is schematicallydepicted in FIG. 29, and includes a motor/transfer case 608 which drivesa first jack screw 610 and a second jack screw 616 via a transfer shaft612 and a transfer case 614. First adjustable walkway 604 is providedwith a pair of threaded plates for threadedly receiving the first andsecond jack screws 610, 616, respectively. When motor/transfer caseturns in a first direction, adjustable walkway 604 is raised. Whenmotor/transfer case 608 turns in an opposite direction, the firstadjustable walkway 602 is lowered. Similarly, second adjustable walkway606 is vertically adjustable through a drive system which includes amotor/transfer case 618, a first jack screw 624 and a second jack screw626 which is driven by motor/transfer case 618 via a transfer shaft 620and a transfer case 622. When motor/transfer case 618 turns in a firstdirection, jack screws 624, 626, which are threaded through respectivethreaded plates in the second adjustable walkway 606, operate to raisethe second adjustable walkway. When motor/transfer case 618 turns in anopposite direction, second adjustable walkway 606 is raised. Secondadjustable walkway 606 is oriented so that it can be aligned with thelower level 574 of horizontal stabilizer platform 568, as is perhapsbest illustrated in FIG. 28.

In operation, dock assemblies 516, 518 are first positioned in a fullywithdrawn orientation, similar to that which is depicted in FIG. 26A,and the slide boards in the nose docking assembly 514 are fullyretracted. At this time, the first and second columns 554, 560 on thedock assemblies 516, 518 are fully extended, and the horizontalstabilizer platform 568, first adjustable walkway 604 and secondadjustable walkway 606 are all positioned in their highest possiblevertical position. This allows the left and right wings 548, 550 of theaircraft 512 to pass beneath dock assemblies 516, 518 as nose section520 is positioned between the left and right sides 522, 524 of the nosedocking assembly 514. Once nose section 520 is so positioned, the leftand right sides 522, 524 of nose docking assembly 514 are verticallyadjusted to the desired position, and the slide boards 546 arepositioned to create working surfaces which are complementary in shapeto the nose section 520 of the aircraft 512.

At this point, the dock assemblies 516, 518 are moved on the respectiverear trolley units 562 to a position more adjacent to the fuselage ofthe aircraft 512, in a manner that is identical to that depicted in FIG.26B. Horizontal stabilizer platform 568, first adjustable walkway 604and second adjustable walkway 606 are adjusted to a more normaloperating position at this point. Then, the forward trolley units 556 ofthe dock assemblies 516, 518 are moved on the respective rail tracks toa position which is more closely adjacent the fuselage, as depicted inFIG. 26C. The assemblies 516, 518 are then moved on rear trolley unit562 so that horizontal stabilizer platform 568 is positioned beneath thehorizontal fin 570 of the aircraft 512. This step is schematicallydepicted in FIG. 26D. As a final adjustment step, each of the dockassemblies 516, 518 are moved on the forward trolley units 556 to aposition which is immediately adjacent the fuselage 512, as is shownschematically in FIG. 26E. At this point, horizontal stabilizer platform568 can be adjusted to a vertical position which is the most convenientto maintenance personnel who will be working on the horizontalstabilizer fin 570. First and second adjustable walkways 604, 606 can belikewise adjusted. In some aircraft, a cargo door is provided in thefuselage between the level of the first adjustable walkway 604 and thesecond adjustable walkway 606. In such aircraft, it may be necessary toadjust the positions of the respective walkways 604, 606 to open thecargo door, and to readjust the positions of the walkways 604, 606 toachieve the most convenient operating position. At this point,maintenance can be quickly and efficiently performed on the aircraft512. To withdraw the aircraft 512 from the system 510, the above processis reversed.

Referring now to FIG. 30, a system for locking a slide board accordingto the invention in place will now be described. A platform 628 isformed by a number of steel members which operate as housings 630 for aplurality of slide boards 632. Slide board 632 could be used in place ofany of the slide boards which are previously disclosed for conforming awork surface to the fuselage of an aircraft or another object. Slideboards 632 have a number of notches 634 defined in an upper edgethereof, as may be seen in FIG. 30.

A wall or housing 638 is attached to a structural plate 636 which isattached beneath platform 628. A pin 640 is mounted to wall 638, as is acam plate 642 which is pivotable about a pivot pin 644 attached to wall638. Cam plate 642 includes a cam surface 646 and an upper surface 648which is in contact with a bottom end of a locking pin 650. Locking pin650 is mounted so as to be freely slidable upwardly and downwardly, andincludes a projection 652 which is sized to fit in any of the notches634. As may be seen in FIG. 30, a lever 654 having a slot 656 definedlongitudinally in a bottom end thereof is also part of the lockingsystem.

When lever 654 is not inserted so that its slot 656 fits over pin 640,locking pin 650 will settle so that its projection 652 is in one of thenotches 634, thereby locking the slide board 632 into a fixed position.Lever 654 is generally stored in a remote location, except when it isdesired to advance or retract slide board 632. To advance a slide board632, lever 634 is inserted downwardly between the slide boards so thatslot 656 receives pin 640. As a result, lever 654 will contact camsurface 646, rotating cam plate 642 in a counterclockwise direction.This causes the upper surface 648 of cam plate 642 to cam locking pin650 upwardly, thereby removing projections 652 from notch 634. At thispoint in time, an operator will push lever 654 in a counterclockwisedirection, causing an ear 658 on a rear surface of lever 654 to engageone of the notches 634 in slide board 632. As a result, slide board 632will advance forwardly out of housing 630. At the end of such a stroke,an operator may slightly withdraw lever 634 and reengage ear 658 with anotch 634 which is further to the rear of the slide board 632. Slideboard 632 may then be advanced further in similar fashion. When slideboard 632 is in its desired position, lever 654 is removed. Locking pin650 will then settle into one of the notches, locking slide board 632 inposition.

When slide board 632 is to be withdrawn, lever 654 is again inserted sothat slot 656 receives pin 640. Locking pin 650 is thus pushed upwardly,removing projection 652 from notch 634. Ear 658 is then positioned in aforward notch 634, and lever 654 is pulled backwardly in a clockwisedirection to retract slide board 632 into the housing 630. This processcan be repeated as many times as is necessary.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

What is claimed:
 1. A docking facility for aircraft maintenance andrepair, comprising:a floor; a guide rail that is fixed with respect tosaid floor; a first column supported by said floor; a second columnsupported by said floor; and a walkway system supported at a firstlocation by said first column and at a second location by said secondcolumn, said walkway being constructed and arranged so as to bepositionable to extend lengthwise along the fuselage of an aircraft toprovide access to the fuselage for maintenance and repair purposes;wherein at least one of said first and second columns is movable formoving said walkway system to a retracted position away from an intendedposition of an aircraft while an aircraft is being moved into or out ofdocking position, said at least one movable column comprising means formovably mounting said one column for movement along said rail, saidmounting means engaging said rail in a manner so as to prevent tippingof said movable column during movement, whereby docking of an aircraftof the facility can be accomplished safely and effectively.
 2. Afacility according to claim 1, wherein both said first and secondcolumns are movable for moving said walkway system to a retractedposition while an aircraft is being moved into or out of dockingposition.
 3. A facility according to claim 1, wherein said mountingmeans comprises a trolley assembly for riding on said rail, said trolleycomprising at least one rail clamp for engaging an underside of saidrail when said walkway system begins to tip.
 4. A facility according toclaim 3, wherein said trolley comprises at least two wheels that ride onsaid rail at the same time, thereby providing stability to said mountingmeans.
 5. A facility according to claim 1, wherein said other of saidfirst and second columns that does not include said mounting meanscomprises a trolley having wheels thereon for permitting said othercolumn to move over said floor.
 6. A facility according to claim 5,wherein said wheels are oriented so that said trolley will tend to moveover said floor in an arcuate motion.
 7. A docking facility for aircraftmaintenance and repair, comprising:a pair of oppositely facing dockingsystems, said docking systems being positioned on opposite respectivesides of an aircraft for maintenance and repair purposes, each of saiddocking systems comprising: a first column; a second column; firstmounting means for mounting said first column for ground-supportedpivotal movement about said second column; second ground-supportedmounting means for mounting said second column for movement along a pathtoward and away from said other, oppositely facing docking system; and awalkway system supported at a first location by said first column and ata second location by said second column, said walkway being constructedand arranged so as to be positionable to extend lengthwise along thefuselage of an aircraft, whereby said systems may be moved away fromeach other during aircraft docking by moving the respective secondcolumns apart along said respective paths and then moving the firstcolumns apart by pivoting the first columns about the second columns. 8.A facility according to claim 7, wherein said second mounting meanscomprises anti-tipping means for preventing said second column and,thus, said walkway from tipping during movement.
 9. A facility accordingto claim 8, wherein said anti-tipping means comprises means for engaginga stationary guide rail when tipping begins to occur.
 10. A method ofperforming maintenance or repairs on a large aircraft, comprising:(a)providing first and second oppositely facing docking systems that eachinclude a first floor-supported column, a second floor-supported column;and a walkway system supported at a first location by the first columnand at a second location by the second column, the walkway beingconstructed and arranged so as to be positionable to extend lengthwisealong the fuselage of an aircraft; (b) moving the first column of thefirst system along a path away from the first column of the secondsystem; (c) moving the second column of the first system away from thesecond column of the second system; (d) moving an aircraft into thespace between the docking systems that was created in steps (b) and (c);(e) moving the second column of the first system toward the secondcolumn of the second system to bring the respective second portions ofthe systems into a position that is adjacent to the fuselage of theaircraft; (f) moving the first column of the first system along a pathtoward the first column of the second system to bring the respectivefirst portions of the systems into a position that is adjacent to thefuselage of the aircraft; and (g) performing a maintenance or repairprocedure on the aircraft while working from the respective walkways onthe systems.
 11. A method according to claim 10, wherein the movementalong the path in steps (b) and (f) comprises a linear motion.
 12. Amethod according to claim 10, wherein the movement in steps (c) and (e)is a pivotal motion about said first column of said first system.